Question

Sarcomere is the functional unit of

• A. Contraction
• B. Relaxation
• C. Contraction and relaxation
• D. None of the above

Answer 1

The correct option is A Contraction

• The ‘A’ and ‘I’ bands are arranged alternately throughout the length of the myofibrils.
  
• In the centre of each ‘I’ band, there is an elastic fibre called ‘Z’ line which bisects it. The thin filaments are firmly attached to the ‘Z’ line.
• The portion of the myofibril between two successive ‘Z’ lines is considered as the functional unit of contraction and is called sarcomere.
• Hence Sarcomere is the unit of contraction.